Coulomb’s law & electric fields worksheet with answers

Free printable Coulomb’s law & electric fields worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy

Two point charges of +5 µC and +8 µC are 2 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².

q₁ = +5 µCq₂ = +8 µCr = 2 cm

F = N

2.Easy

Two point charges of +4 µC and −8 µC are 10 cm apart. Find the magnitude of the electric force F between them. Use k = 8.99 × 10⁹ N·m²/C².

q₁ = +4 µCq₂ = −8 µCr = 10 cm

F = N

3.Medium

A charge of +6 µC and a charge of −10 µC are 20 cm apart. Point P lies on the line between them, 12 cm from the first charge. Find the magnitude of the electric field E at P.

q₁ = +6 µCq₂ = −10 µCr₁ = 12 cmr₂ = 8 cm

E = N/C

4.Medium

Charges of +6 µC and +2 µC are 20 cm apart. At what distance x from the +6 µC charge, on the line between them, is the electric field zero?

q₁ = +6 µCq₂ = +2 µCd = 20 cm

x = cm

5.Hard

Charges of +8 µC and −8 µC are 16 cm apart. Point P lies 4 cm from the midpoint between them, on the perpendicular bisector. Find the magnitude of the electric field E at P. Use k = 8.99 × 10⁹ N·m²/C².

q₁ = +8 µCq₂ = −8 µCd = 16 cmh = 4 cm

E = N/C

6.Hard

Three positive point charges sit at the corners of a right triangle: q₃ = 4 µC is at the right-angle corner, q₁ = 8 µC is 4 cm from it along one side and q₂ = 2 µC is 3 cm from it along the other side. Find the magnitude of the net electric force F on q₃.

q₁ = 8 µCq₂ = 2 µCq₃ = 4 µCr₁₃ = 4 cmr₂₃ = 3 cm

F = N

Answer key

1. F = 899 N
2. F = 28.77 N
3. E = 1.779 × 10⁷ N/C
4. x = 12.68 cm
5. E = 1.608 × 10⁷ N/C
6. F = 196.8 N

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